Kenneth W. Collier. Physical modalities and the system E. Notre Dame Journal of Formal Logic, 14(2):185-194, 1973. [doi]
@article{Collier73,
title = {Physical modalities and the system E},
author = {Kenneth W. Collier},
year = {1973},
doi = {10.1305/ndjfl/1093890892},
url = {http://dx.doi.org/10.1305/ndjfl/1093890892},
researchr = {https://researchr.org/publication/Collier73},
cites = {0},
citedby = {0},
journal = {Notre Dame Journal of Formal Logic},
volume = {14},
number = {2},
pages = {185-194},
}